The Decomposition Mechanism of Titania Film with Nanotube Structure

Abstract

The ordered nanochannel-array of anodic titanium oxide (ATO) is formed on the electro-polished titanium substrate. This reproducible procedure of long-range ordered nanochannel ATO retains 170 nm films in length. The process is deduced by electrochemically and thermodynamically; from high defect structure of porous ATO and small sizing of decomposing TiO2cluster on the surfaces. In this study, ATO with 68.2% porosity is discomposed at 581 °C under oxygen partial pressure of 4×10-9atm. The pore of ATO has wall thickness of 25 nm with density of 8×109per cm2under 1.2 vol.% hydrofluoric acid (HF) and 10 vol.% sulfuric acid (H2SO4) electrolyte for 90 seconds of 20 V of applied potential. The pore size is 100 nm in diameter and uniformly distributed with 120 nm pore-to pore distance in between.